ACPAtmospheric Chemistry and PhysicsACPAtmos. Chem. Phys.1680-7324Copernicus GmbHGöttingen, Germany10.5194/acp-11-5471-2011Seasonal variations and vertical features of aerosol particles in the Antarctic troposphereHaraK.13OsadaK.2Nishita-HaraC.24YamanouchiT.11National Institute of Polar Research, Tokyo, Japan2Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan3now at: Department of Earth System Science, Faculty of Science, Fukuoka University, Fukuoka, Japan4now at: Advances Materials Institute, Fukuoka University, Fukuoka, Japan15062011111154715484This work is licensed under a Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/This article is available from http://www.atmos-chem-phys.net/11/5471/2011/acp-11-5471-2011.htmlThe full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/5471/2011/acp-11-5471-2011.pdf

Tethered balloon-borne aerosol measurements were conducted at Syowa Station,
Antarctica during the 46th Japanese Antarctic expedition (2005–2006). The
CN concentration reached a maximum in the summer, although the number
concentrations of fine particles (<i>D<sub>p</sub></i>>0.3 μm) and coarse
particles (<i>D<sub>p</sub></i>>2.0 μm) increased during the winter–spring. The
CN concentration was 30–2200 cm<sup>−3</sup> near the surface (surface – 500 m)
and 7–7250 cm<sup>−3</sup> in the lower free troposphere (>1500 m). During the
austral summer, higher CN concentration was often observed in the lower free
troposphere, where the number concentrations in fine and coarse modes were
remarkably lower. The frequent appearance of higher CN concentrations in the
free troposphere relative to continuous aerosol measurements at the ground
strongly suggests that new particle formation is more likely to occur in the
lower free troposphere in Antarctic regions. Seasonal variations of size
distribution of fine-coarse particles show that the contribution of the
coarse mode was greater in the winter–spring than in summer because of the
dominance of sea-salt particles in the winter–spring. The number
concentrations of fine and coarse particles were high in air masses from the
ocean and mid-latitudes. Particularly, aerosol enhancement was observed not
only in the boundary layer, but also in the lower free troposphere during and
immediately after Antarctic haze events occurring in May, July and
September.